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Life cycle carbon dioxide emissions for fill dams
Carbon dioxide (CO2) emissions must be reduced to solve environmental problems such as global warming and climate change, which are getting worse with each day. In Korea, 42% of total carbon emissions are generated by the construction industry; therefore, it seems urgent to reduce these carbon emissions. Especially, because the size of agricultural reservoirs is large, and they are distributed nationwide, effective environmental management is important in Korea. Professor Son and his research team, including Sookack Noh, Jaesung Park of Department of Landscape Architecture and Rural Systems Engineering, published a paper titled “Life cycle carbon dioxide emissions for fill dams” in November 2018, proposing ways to evaluate CO2 emissions related to fill dams (earth dam) and presenting characteristics of CO2 that can be used to effectively address environmental problems in infrastructure. In this study, Professor Son’s research team selected four fill dams for research and adopted the life cycle assessment (LCA) method to measure CO2 emissions generated during construction for using and repairing them.
LCA refers to a method used for assessing environmental effects by quantifying materials released throughout all processes, from generation of materials to processing, transportation, and construction. CO2 emissions from each stage of construction, using, and repairing were measured by dividing them into CO2 emissions from material production, those from equipment use, and those from transportation. The amount of CO2 emitted during the construction phase is measured by the total amount of CO2 generated from materials, equipment, and transport used for construction.
Professor Son revealed that during the construction phase of a fill dam, the CO2 emitted from material production was more than that emitted while using equipment or transportation. This is because the materials were relatively close to the construction site, and the usage of equipment and transportation of the materials was relatively low; thus, the amount of CO2 emitted from equipment and transportation was relatively low.
Fig 1. CO₂ emissions over time.
In addition, when CO2 emissions according to the usage period were assessed, they were found to have increased cumulatively over time owing to the maintenance process in all four fill dams. In 0–40 years without a repair process, CO2 was emitted only owing to power consumption, and the emitted amount was insignificant; therefore, the trend of the increase was not apparent. High increases in repair processes occurred between 40–50 years of service, wherein repair processes were concentrated. Particularly, in Woongyang and Bocheong districts, where the size of the dam body is large, the maintenance process showed a relatively large increase each time the maintenance process was conducted.
Professor Son’s research team compared CO2 emissions from the following three repair methods: cross-section repair, grouting, and riprap repair. CO2 emissions from grouting were the highest, and those from cross-section repair were the lowest. In addition, CO2 emissions from all repair methods were affected by the scale of the repair of the fill dam; CO2 emissions in Woongyang, which is the largest in size, were the highest.
In this study, Professor Son concluded that to reduce CO2 emissions from a fill dam, construction materials should be replaced with environmentally friendly materials that emit less CO2, and efficient repair methods that reduce CO2 emissions must be used.
In this study, Professor Son’s research team calculated CO2 emissions according to materials, material transportation methods, and processing methods required for maintaining a fill dam. In particular, Professor Son’s research team found significant results; they measured CO2 emissions by applying LCA methodology to different dam structures. Simultaneously, Professor Son pointed out that the energy consumption of each process is not known precisely; therefore, further research is needed. Because construction accounts for more than half of the total CO2 emissions, reduction in CO2 emissions in the construction sector can have a significant impact; therefore, Professor Son expects to find an efficient process to reduce CO2 emissions that are identified as a cause of global warming and are expected to contribute to environmental problems. Following this research, Professor Son’s research team will continue to study to contribute to sustainability by recycling waste from power plants. In addition to researching the utilization of recycled resources, we expect to demonstrate a higher sustainability by limiting the transport distance by measuring CO2 emissions according to the transport distance when utilizing recycled resources. Professor Son pointed out that it is necessary to improve awareness of alternatives via recycling.
《Professor Younghwan Son》
《Professor Younghwan Son》
Written by Jisu Lim, Ockki Cho
Student Press of College of Agriculture and Life Sciences